Wound covering

ABSTRACT

A non-contact wound covering for covering a wound. A peripheral sealing ring is covered by a barrier layer and this assembly is attached to the skin with an adhesive. The barrier layer and peripheral sealing ring together define a treatment volume over the wound. The barrier layer may include active and passive heaters and the sealing ring may dispense water to control the humidity of the treatment volume. One form of active heat is the transfer of a heated fluid to the wound covering.

This application is divisional of application Ser. No. 08/999,353, filedDec. 29, 1997 which is a continuation of 08/356,325 filed Feb. 21, 1995now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a wound covering for wound treatment. Thewound covering overlays the wound area without touching the wounditself. The wound covering preferably controls the temperature, humidityand other aspects of the environment at the wound site.

2. Technical Background

Traditional wound coverings such as bandages are used to mechanicallyclose wounds. Such bandages typically cover and touch the wound. Bandagecontact with the wound and can interfere with the healing process.

The benefits of application of heat to a wound are known and documentedbenefits include: increased cutaneous and subcutaneous blood flow;increased partial pressure of oxygen at the wound site; increased immunesystem functions, including increased migration of white blood cells tothe site.

However, in modern times, heat therapy for the treatment of wounds andinfection has been difficult to achieve in practice. Additionally theavailability of antibiotics have taken precedence over other therapiesfor the treatment of wounds and topical infections.

The benefits of controlling other environmental parameters around thewound site are not as well known. Controlling the humidity at the woundsite as well as the benefits of isolating the wound have not beenextensively studied and documented.

SUMMARY OF THE INVENTION

The preferred form of the wound covering includes a peripheral sealingring which, in use, completely surrounds the area of the wound. Theupper surface of the peripheral sealing ring is spanned by a continuousbarrier layer which is preferably transparent and substantiallyimpermeable. An adhesive and a suitable release liner is applied to thelower surface of the peripheral sealing ring to facilitate theapplication of the wound covering to the patient's skin. Once inposition, the sealing ring and the barrier layer define a woundtreatment volume which surrounds the wound.

In accordance with actively heated embodiments of the invention, thebarrier layer may include a pocket adapted to receive an active heater.An alternate form of the invention provides for the transport of heatedair from a remote source, to the wound treatment volume. In the activeheater embodiments a thermostat and/or a pressure activated switch maybe used to control the heating effects of the electrically poweredheater. Passively heated embodiments are contemplated as well. Thesepassive versions of the device include the use of thermally insulatingcoverings which retain body heat within the treatment volume. Thesereflectors or insulators may be placed in a pocket formed in the barrierlayer. Each of these heated embodiments promote wound healing bymaintaining the wound site at a generally elevated but controlledtemperature.

In general the peripheral sealing ring is made from an absorbentmaterial which may acts as a reservoir to retain and dispense moistureinto the treatment volume increasing the humidity at the wound site. Thereservoir may also contain and deliver drugs and the like to promotehealing.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative but not limiting embodiments of the invention are shown inthe attached drawings. Throughout the several figures like referencenumerals refer to identical structure throughout, in which:

FIG. 1A is an exploded view of the wound covering;

FIG. 1B illustrates an assembled view of the wound covering of FIG. 1A;

FIGS. 2A and 2B is a view of an alternate wound covering;

FIG. 3A is an exploded view of an alternate wound covering;

FIG. 3B is an assembly view of the wound covering of FIG. 3A;

FIG. 4 is a side elevation view of a wound covering;

FIG. 5 is an enlarged top plan view of a wound covering;

FIG. 6 is an enlarged sectional view taken along line A--A of FIG. 5;

FIG. 7 is a bottom view of the wound covering of FIG. 4;

FIG. 8A is an exploded view of an alternate wound covering:

FIG. 8B is an assembly view showing the air flow through the woundcovering;

FIG. 9A is a perspective view of an alternate wound covering;

FIG. 9B is a side view of the wound covering of FIG. 9A;

FIG. 10 is a perspective view of an alternate wound covering;

FIG. 11A is a perspective view of an alternate wound covering;

FIG. 11B is a side cross-sectional view of the wound covering of FIG.11A;

FIG. 11C is a view of the wound covering of FIG. 11A;

FIG. 12 is a perspective view of an alternate connector apparatus forthe wound covering;

FIG. 13A is an alternate connector arrangement for the wound covering;

FIG. 13B is a side sectional view of the wound covering of 13A;

FIG. 14 is a view of a rigid connector for engagement with a woundcovering;

FIG. 15 is an alternate fluid inlet line for the wound covering;

FIG. 16A is a view of a two ply barrier layer wound covering;

FIG. 16B is a cross-sectional view of the wound covering of 16A;

FIG. 17 is an alternate wound covering;

FIG. 18A is an alternate wound covering;

FIG. 18B is a side sectional view of the wound covering of FIG. 18A; and

FIG. 19 is a view of an alternate wound covering.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a non-contact wound covering forcontrolling the local environment at a wound site on a patient. Thewound covering protects the wound from contamination by materials fromthe outside environment and also prevents the wound from site fromsheading contaminants into the local environment of the patient, i.e.the hospital room. The treatment volume formed over the wound site canbe controlled to create an optimal healing environment. The word "wound"as used herein refers generically to surgical incisions, ulcers, orother lesions or breaks in the skin.

Each embodiment of the wound covering includes three basic element.First a vertical wall is provided to encircle the wound area on thesurface of the patient's skin. This vertical structure is selfsupporting and provides an upper surface to support a barrier layerabove the level of the wound. This structure is referred to throughoutas the peripheral sealing ring. The next element is a barrier layerwhich is attached to the peripheral sealing ring. Together theseelements form an enclosure or wound treatment volume over the woundsite. The fact the barrier layer does not contact the wound itselfpromotes healing by minimizing mechanical stresses on the tissues. Thebarrier layer spans the entire wound area and attaches to the peripheralsealing ring. The third element is an adhesive and a complimentaryrelease liner assembly which is attached to the lower surface of thesealing ring to facilitate attachment of the wound covering to the skinof the patient. As will be discussed in the various examples andillustrations detailed below, the three basic components of the woundcovering are combined with other elements to provide an optimal healingenvironment at the wound site.

In accordance with the invention the climate within the wound treatmentvolume may be controlled. Typically the temperature, humidity, and gascomposition is controlled. Also aerosolized medications or compounds canbe released into this volume as well. The above list is exemplary of theclimate controls which may promote healing of the wound, and is notintended to limit the scope of the present invention. It will beunderstood by those skilled in the art that numerous other climatefactors can be controlled within the treatment volume of the presentwound covering system without departing from the scope of the invention.

FIG. 1A illustrates an exploded view of the wound covering 50. In thisembodiment the peripheral sealing ring 52 is substantially square inoutline. The peripheral sealing ring 52 is intended to be attached touninjured skin surrounding the wound area 54 using an adhesive 56. Inthis embodiment a layer of adhesive hydrogel is shown as the adhesive56. In this embodiment the peripheral sealing ring 52 is preferablyconstructed of an open cell hydrophilic foam plastic having a sealedouter surface 58 which isolates the wound from the environment. Theperipheral sealing ring is fabricated from a material which is stiff butwhich may conform to the curved surface of the patient's body. The innersurface 60 of the sealing ring 52 is preferably porous or absorbent sothat it can form a reservoir to contain and release moisture or watervapor into the air within the treatment volume 62 to create a highhumidity environment if desired. Additionally, the hydrophilic absorbentnature of the peripheral sealing ring 52 absorbs fluids and bloodweeping from the wound.

A barrier layer 64 is preferably attached to the upper surface 66 of theperipheral sealing ring 52 to seal the treatment volume 62. The barrierlayer 64 is preferably constructed of a clear flexible plastic film,such as polyethylene or polyvinylchloride. In this embodiment a woundtracing grid 68, also constructed of a clear flexible material, mayoptionally be attached to the barrier layer 64 so that the physician candraw the wound as an aid to track the healing process of the wound. Thewound tracing grid preferably contains a labeling area 70 foridentifying the patient, date when the wound was traced, and otherpatient medical data.

It will be understood by those skilled in the art that the volume of theperipheral sealing ring 52 will depend on the structural strength of thesupport material and the amount of fluid absorption desired.Additionally, the total area of the peripheral sealing ring 52 isdependent on the size of the wound. For example, larger wounds and moreflexible covers will require a thicker sealing ring so that the centerof the cover does not touch the wound.

The upper surface 66 of the peripheral sealing ring 52 is preferablysealed by extending the barrier layer 64 over the entire upper surface66 as seen in the drawing. The adhesive 56 for attaching the peripheralsealing ring 52 to the wound area 54 may take any form however thepreferred adhesive is a preferably a two-faced hydrogel which attachesto the lower surface 72 of the peripheral sealing ring 52. This adhesive56 permits the attachment of the peripheral sealing ring 52 to thepatient's skin. Finally, the peripheral sealing ring 52 may serve as areservoir for retaining water or medicaments in the treatment volume 62in order to maintain a high humidity in the air within the volume. Watermay be added to the peripheral sealing ring 52 at any time duringtreatment.

It will be understood by those skilled in the art that the peripheralsealing ring 52 can be supplied in a variety of shapes and sizes toaccommodate various wounds. The shapes may include circles, squares, orrectangles. Although it is preferred to dispense the wound covering as aunitary assembly it should be apparent that individual segments ofperipheral ring material could be assembled into any shape necessary toform a perimeter around the wound area. Likewise, the barrier layer 64and wound tracing grid 68 could be provided in large sheets which may becut to size and then attached to the peripheral sealing ring.

FIG. 1B is an assembled view of the wound covering 50 of FIG. 1A. Todispense the assembled product a release liner 74 is applied to theadhesive 56. The release liner may span the entire lower surface of thecovering to maintains the sterility of the treatment volume 62. Therelease liner 74 preferably has a grip tab 76 to facilitate removal ofthe liner 74 from the wound covering 50 immediately prior to applicationof the wound covering 50 to the patient.

FIGS. 2A and 2B illustrate an alternate embodiment of the wound covering80 utilizing passive heating of the treatment volume 62. Because heat isconstantly being radiated from the body surface, the insulationproperties of the trapped air within the treatment volume 62 will reducethis heat loss. By adding an infrared reflector 82 over the treatmentvolume 62, the infrared heat from the body can be reflected back to theskin for added passive heating.

One edge 84 of the wound tracing grid 86 is preferably not attached tothe barrier layer to form an envelope or pocket 94 between the woundtracing grid 86 and the barrier layer. A piece of reflective foilmaterial 88 may be inserted into the pocket 94. A thin layer ofinsulating material 90 may optionally be attached to the foil layer 88to enhance heat retention and to provide the foil layer 88 withadditional resiliency. A tab 92 is preferably attached to the infraredreflector 82 to allow easy insertion and removal from the pocket 94 andthe wound covering 80.

FIGS. 3A and 3B illustrate an alternate embodiment of a non-contactwound covering 108 utilizing active heating of the treatment volume 112.Small to medium sized wounds (up to approximately six inches indiameter) may be safely and easily heated utilizing the foil heaterassembly 100. The heater assembly 100 preferably comprises apressure-sensitive switch 102, an insulating layer 104, and a foilheater element 106.

The pressure-sensitive switch 102 is preferably laminated to the upperlayer of the heater assembly 100. The purpose of the switch 102 is toshut off power to the heater element 106 in the event that externalpressure is applied to the wound covering 108 with sufficient force tocause the heater element 106 to contact the skin or wound below. This isan important feature to prevent the possibility of applying heat andpressure to the skin at the same time. The combination of heat andpressure is known to cause burns even at low temperatures (40° C.)because the pressure prevents blood flow in the skin making itsusceptible to thermal injury. The pressure-sensitive switch 102preferably covers the whole heater assembly 100 so that pressure appliedanywhere to the surface of the heater assembly 100 will deactivate theheater element 106.

It will be understood that a variety of devices are suitable for use asthe pressure-sensitive switch 102. For example, force sensing resistorsresemble a membrane switch which changes resistance inversely withapplied force. Devices of this type offer the substantial advantage ofbeing low cost, flexible, and durable. It will be understood by thoseskilled in the art that a variety of other force sensing switch devicesmay be utilized as well.

The heater element 106 is preferably a thin film type resistance heaterwhich is commercially available. Such thin film resistance heatersutilize low voltage, minimizing the electrical risk to the patient andallowing for battery-powered mobility. The heater element 106 ispreferably sized for each wound covering 108. In actual use,the foilheater element 106 is preferably provided in large sheets with a pair ofelectrical leads 110 along one edge.

The foil heater assembly 100 is preferably inserted into a pocket 114formed between the wound tracing grid 86 and the barrier layer asdiscussed above. Finally, a temperature monitoring device, such as aliquid crystal temperature monitor, may be applied to an upper surfaceof the foil heater assembly 100 or within the treatment volume 112 tomonitor the temperature within the treatment volume 112.

FIG. 4 and FIG. 5, illustrate an alternate embodiment of the woundcovering 10. In this embodiment the wound covering 10, includes agenerally circular head, designated generally at 12, which transitionsto an elongated non-kinking, collapsible air supply or hose 14.

The apparatus, as illustrated in FIG. 4, is connected by suitable supplyline or tube 16 to a source 18 of thermally controlled air which isschematically illustrated. The term air as used herein is intended toencompass mixtures of gases of controlled composition. The apparatus isconstructed to apply a continuous stream of thermally controlled air toa wound treatment volume. While the apparatus was conceived andconstructed for applying a heated stream of air, it may also be used toapply a cooled stream of air if required.

The specific form of the apparatus and details of construction can bestbe understood by reference to the various figures. The overallappearance of the wound covering is best seen in FIG. 4 and FIG. 5. Itis preferred to construct the apparatus from top and bottom sheets ofthin heat-sealable polymer film which overly one another. A top sheet ormembrane 20 overlies a bottom sheet or membrane 22 and they are heatsealed together along a plurality of seal lines, including a continuousouter seam 24, which extends in a circle around the head 12 andcontinues in a sinusoidal or convoluted fashion along and forming theair tube portion 14. An inner continuous circular seam 26 is provided asbest seen in FIG. 6 and in FIG. 7. This inner seam secures the sheetstogether along a continuous circle to form the inner wall of a torusdefining a supply volume 28.

The inner circular portion of the two sheets lying in the plane withinthe center of the supply volume 28 forms a wall 30 separating a lowerwound treatment volume 32, from an upper insulation chamber 34. The wall30 includes multiple apertures 36 formed by making small circular seals38 and cutting and removing circular portions within the circular seals38. Thus, a wall 30 with a plurality of apertures 36 is formed betweenthe wound treatment volume 32 and insulation chamber 34. A plurality ofapertures 40 are formed in the common circular wall surrounding thetreatment volume 32 for distributing and conveying heated air or gasesfrom the supply volume 28 into the wound treatment volume 32.

The heated air flowing into the treatment volume 32 bathes and contactsthe wound surface of a patient's body 42. The air circulates throughoutthe wound treatment volume 32, and then passes through the apertures 36into the upper or insulating chamber 34, where it then passes through acircular filter 44 forming an outer wall of the insulation chamber 34.The filter 44 filters the air leaving the wound treatment volume to trapcontaminants shed from the wound. The filter 44 may be constructed of afilter paper bonded along its periphery to the outer tangential walls ofthe housing forming the torus or supply chamber 28. The filter paperalso provides an insulating layer which suppresses loss of heat byradiation through the upper wall 30.

The lower surface of the head 12 as shown in FIG. 6 and FIG. 7, ispreferably provided with a peripheral sealing ring 46 made of anabsorbent material such as foam and bonded by suitable adhesive to thewalls of the housing and the skin of the patient around the wound.Preferably, the foam or cotton peripheral sealing ring 46 is providedwith a peel-off tape so that it adheres to the wall of the housing andon the other side to the skin of the patient. The adhesive or tape holdsthe apparatus in place and prevents airflow escape between the deviceand the skin of the patient. The absorbent material of the ring absorbsweeping blood and fluids and insulates the skin from direct heat in thetube.

The supply hose 14 is designed to be non-kinking by forming it ofsymmetrically convoluted flexible material. The hose and housing areintegrally formed essentially of a unitary structure, such as a thinfilm membrane. The supply hose section 14 is inflatable upon theapplication of heated air through the supply line 16. The indentationsin the hose section 14 permit it to bend without kinking and, thus,differentiate from a straight tubular hose which may kink when bent.

Since the thermal body treatment apparatus of the invention and thesupply hose section are formed from two, thin, sealed-togethermembranes, the hose, and in fact the entire apparatus, is collapsible.This prevents the possibility of applying heat and pressure to the skinas might happen if a disoriented patient rolled over on the device.Instead, the weight of the patient's body would collapse the device,obstructing the flow of air, and preventing the application of heat.

The film membrane may preferably be transparent to enable viewing thewound without removal. However for cosmetic reasons the barrier layermay be opaque. The filter paper 44 is attached across the tangentialsurfaces of the toroidal housing, thus providing a large area of filterfor the escaping air. The head of the apparatus maybe about one foot indiameter for most applications. However, it may be made smaller forcertain other applications.

FIG. 8A illustrates an exploded view of an alternate embodiment of anon-contact wound covering 120 with climate control within the treatmentvolume 122. An inflatable structure 124 is preferably attached to afluid inlet line 126 at a fluid inlet port 129 on the perimeter of theinflatable structure 124. The inflatable structure 124 is preferablyattached to an absorbent peripheral sealing ring 128, which is in turnattached to the wound area 54 by a suitable adhesive 56. The peripheralsealing ring 128 preferably has a sealed outer surface and a porousinner surface which performs the same function as the peripheral sealingring 52 discussed above. A barrier layer 130 having an exhaust filter132 is attached to top surface 134 on the inflatable structure 124.

Turning now to the assembly illustrated in FIG. 8B, a gas illustrated bythe arrows A, is introduced into the inflatable structure 124 from anexternal source (not shown) through the inlet line 126. The gaspressurizes the inflatable structure 124 in order to maintain thebarrier layer 130 and exhaust filter 132 in an elevated positionrelative to the wound area 54. The inner surface 136 of the inflatablestructure 124 preferably has a plurality of apertures 138 through whichthe fluid is introduced into the wound treatment volume 122. As thepressure within the treatment chamber increases, excess pressure isrelieved through the exhaust filter 132. In this fashion, various fluidsor gases can be introduced into the wound treatment volume 122.

The use of the term "fluid" in the context of this application refers toboth liquid and gaseous materials, and combinations thereof. In oneembodiment, oxygen may be introduced into the treatment volume 122through the apertures 138 of the inflatable structure 124. The presenceof oxygen within the wound treatment volume 122 may increase the oxygenavailable to the superficial layer of growing cells in the wound area54. Nitric oxide may alternatively be infused into the treatment volume122. Nitric oxide (NO) is a potent vasodilator which in theory may beabsorbed across the wound surface and increase localized blood flow. Avery small concentration of NO (parts per million) may provide thiseffect. NO may also be pre-absorbed into the absorbent peripheralsealing ring 128 and then allowed to passively diffuse into the volumeonce it is applied to the wound. Finally, gaseous or aerosolizedmedications or compounds may be introduced into the gas flow enteringthe treatment volume 122.

FIG. 9A and FIG. 9B illustrate an alternate embodiment of the climatecontrol system discussed above wherein a fluid inlet line 140 may formpart of a barrier layer 142 The barrier layer 142 is unitary with thefluid inlet line 140 and is preferably attached to an exhaust filtermedia 144 to allow excess pressure to be released from the woundtreatment volume 146. In this embodiment, the filter media 144 formspart of the barrier 142. The arrows "A" in FIG. 9B illustrate themovement of the fluid though the fluid inlet line 140, the treatmentvolume 146, and the exhaust filter 144.

FIG. 10 illustrates an alternate embodiment wherein an exhaust filter154 is retained in a recess 150 formed in one side of a peripheralsealing ring 152. This structure allows the excess fluid to be exhaustedthrough the side of the peripheral sealing ring 152, rather than throughthe top, as illustrated in FIG. 9A and 9B.

FIG. 11A is a perspective view of the embodiment illustrated in FIG. 9Awherein a connector 160 on the end of a fluid supply line 162 engageswith an opening 164 on the fluid inlet line 140. FIG. 11B illustrates aside view of the fluid supply line 162 as it engages with the fluidinlet line 140. FIG. 11C illustrates the embodiment of 11A and 11B wherethe fluid inlet line 140 is folded over the top of the peripheralsealing ring 152 to seal the treatment volume 146 when the supply line162 is uncoupled.

FIG. 12 illustrates an alternate embodiment in which a fluid inlet slot170 engages with a rigid connector 172 on a fluid inlet line 174. Thefluid inlet slot 170 forms an opening in one portion of the peripheralsealing ring 176. The opening is in fluid communication with thetreatment volume 178. This configuration allows for quick disconnect ofthe fluid inlet line 174 from the wound covering 180 to provide thepatient with additional mobility.

FIG. 13A is a perspective view of an alternate non-contact woundcovering 190 having a fluid inlet connector 192 attached to a topsurface 194 of the peripheral sealing ring 196. The fluid inletconnector 192 preferably contains an inlet filter media 198. A rigidconnector 200 on a fluid inlet line 202 mates with the fluid inletconnector 192. As illustrated in FIG. 13B, a cover 204 extends from thetop of the fluid inlet connector 192 across the top of the peripheralsealing ring 196 where it engages with an exhaust filter media 206. FIG.14 illustrates the embodiment of FIGS. 13A and 13B utilizing anon-disposable fluid supply line 210.

FIG. 15 illustrates an alternate embodiment which utilizes a manifoldstructure 220 as part of the fluid inlet line 222 to provide evendistribution of the fluid being introduced into the treatment volume224. The fluid inlet line 222 preferably has a series of seals 226 alongits edge which are interrupted by a plurality of side openings 228 fromwhich the fluid can be transmitted into the treatment volume 224. Theembodiment disclosed in FIG. 15 illustrates an exhaust filter 230recessed into the side of the peripheral sealing ring 232. However, itwill be understood that a variety of exhaust filter configurations arepossible with the disclosed manifold structure 220.

FIGS. 16A and 16B illustrate an alternate wound covering 240 with a topbarrier layer 242 and a lower layer 244 having a plurality of holes 246.As is illustrated in FIG. 16B, the top cover forms the barrier layer 242and it extends substantially across the area of the peripheral sealingring 248. The lower layer 244 likewise extends across the peripheralsealing ring 248. An upper insulating layer 250 is formed between thelower layer 244 and the top of the barrier layer 242. Fluid in the fluidinlet line 252 is directed into the upper insulating layer 250. Thepressurized fluid in the upper insulating layer 250 passes through theholes 246 into the treatment volume 254. The holes 246 in the lowerlayer 244 provide generally even distribution of the fluid within thewound treatment volume 254. An optional seal 258 may be formed in thecenter portion of the barrier layer 242 and the lower layer 244 toprovide the layers with additional structural support. An exhaust filtermedium 256 is provided in a recess along one side of the peripheralsealing ring 248 to relieve pressure in the treatment volume 254.

FIG. 17 illustrates an alternate embodiment of a non-contact woundcovering 260 utilizing semi-rigid supports 262 to retain the barrierlayer 264 above the wound area. It will be understood by those skilledin the art that a variety of semi-rigid supports 262 may be utilized forthis application. For example; plastic or resilient rubber materials mayprovide sufficient support to the barrier layer 264 with a minimum riskof injuring the patient.

FIG. 18A and FIG. 18B illustrate an alternate exhaust filter medium 270with an enlarged surface area to accommodate larger volumes of air flowthrough the non-contact wound covering 280. The exhaust filter isincorporated into the fluid inlet line 272. The fluid inlet line 272also forms a portion of the barrier layer 274, which is in turn attachedto the peripheral sealing ring 276. As is best shown in FIG. 18B, fluidillustrated as the arrows "A" is introduced into the fluid inlet line272, where it is directed into the wound treatment volume 278, past thewound area and out through the exhaust filter medium 270.

FIG. 19 illustrates a bi-directional line 290 with a center divider 292.Fluid is introduced into the fluid inlet line 294 where it proceedsthrough a fluid inlet port 296 into the treatment volume 298. The fluidthen is forced through a fluid outlet port 300 where it is driven awayfrom the treatment volume 298 in a fluid outlet line 302. It will beunderstood by those skilled in the art that it would be possible toutilize separate fluid inlet and outlet lines to achieve the sameresult.

While the invention has been illustrated by means of specificembodiments, it will be evident to those skilled in the art that manyvariations and modifications may be made therein. However, it is to beunderstood that the scope of the present invention is to be limited onlyby the appended claims.

What is claimed:
 1. A wound covering for application to a wound area ofa body, the wound covering comprising:a sealing ring, having an uppersurface and a lower surface, defining an open cavity for placement overand sealing around the wound area; a barrier layer spanning the sealingring and attached to the sealing ring proximate the upper surface to bespaced apart from the wound area by the sealing ring; the barrier layercomprising a gas permeable film; the sealing ring for supporting thebarrier layer above the level of the wound area; the sealing ring andthe barrier layer together defining a wound treatment volume; wound areaattachment means, proximate the lower surface, for permitting attachmentof the sealing ring to the wound area; and means proximate the barrierlayer for retaining a heater above the level of the wound area.
 2. Thewound covering of claim 1 in which the sealing ring comprises aconformal polymeric foam ring.
 3. The wound covering of claim 1 furthercomprising a heater, retained over the barrier layer by the means, forheating the wound treatment volume and wound area.
 4. The wound coveringof claim 3 in which the heater comprises an active heater.
 5. The woundcovering of claim 3 in which the heater comprises a passive heatreflecting layer.
 6. The wound covering of claim 1 in which the meanscomprises a pocket adapted for receiving the heater.
 7. The woundcovering of claim 1 in which the wound area attachment means includes anadhesive applied to the lower surface and a release liner releasablyattached to the adhesive.
 8. The wound covering of claim 4 furthercomprising a switch to turn off the active heater.
 9. The wound coveringof claim 4 further comprising a thermostat coupled to the active heaterto regulate the temperature of the wound treatment volume.